Organ and tissue generation from cells provides promising treatments for a number of pathologies, thereby making stem cells a central focus of research in many fields. Human stem cells are capable of generating a variety of mature human cell lineages. Transplantation of such cells has provided a clinical tool for reconstituting a target tissue, thereby restoring physiologic and anatomic functionality. The application of stem cell technology is wide-ranging, including tissue engineering, gene therapy delivery, and cell therapeutics for disorders including malignancies, inborn errors of metabolism, hemoglobinopathies, and immunodeficiences.
An obstacle to realization of the therapeutic potential of stem cell technology has been difficulty in obtaining sufficient numbers of human stem cells. One source of stem cells is embryonic or fetal tissue. Embryonic stem and progenitor cells have been isolated from a number of mammalian species, including humans. The derivation of stem cells from embryonic or fetal sources, however, has raised many ethical and moral issues.
Stem cells also have been isolated from adult tissues. Methods for isolation of stem cells from adult sources often yield only limited quantities of cells and/or cells having limited ability to differentiate.
Postpartum tissues have generated interest as an alternative source for human stem cells. For example, methods for recovery of stem cells by perfusion of the placenta or collection from umbilical cord blood have been described. A limitation of stem cell procurement from these methods has been an inadequate volume of cord blood or quantity of cells obtained.
Thus, alternative sources of adequate supplies of cells having the ability to differentiate into an array of cell lineages for cryopreservation and/or use in clinical applications remain in great demand. Such cells may be used in drug screening assays, for cryopreservation and/or banking, and for diagnostic and therapeutic applications.